The objective of this long-term project, carried out partly within the framework of WHO/UNEP/ILO International Programme on Chemical Safety (IPCS), is to prepare evaluations of biological effects and health hazard assessments of selected chemicals, including evaluation of toxicological methods on which published data are based. Focus has been on the assessment of 2,6-toluene diamine, phthalic acid esters, and selected metals and metal compounds. The methodological component of the project dealt with methods for assessing the effects of chemicals on reproductive function, methods for estimating exposure and quantifying risk to human health, biological tests in the evaluation of mutagenicity and carcinogenicity of air pollutants, and principles and methods for toxicity evaluation of chemicals.